Percussive hand-tool.



PATENTED AUG. 1, 1905.

H. POTTER.

PERCUSSIVE HAND TOOL.

2 SHEETS-SHEET 2.

APPLICATION FILED FEB. 23,1905.

[NVEN TOR flw B 1 Z/MQ W.

' Altomey HENRY POTTER, OF BROMLEY, ENGLAND.

PERCUSSIVE HAN D-TOOL.

Specification of Letters Patent.

Patented Aug. 1, 1905.

Original application filed December 17, 1904, Serial No. 237,307. Divided and this application filed February 23, 1905. $erial To all whom it may concern:

Be it known that I, HENRY POTTER, a subjec of the King of Great Britain and Ireland, residing at Bromley, in the county of Kent, England, (whose post-oflice address is 3 Scotts Villas, Heathfield Road, Bromley, in the county of Kent, England.) have invented an Improved Percussive Hand Tool Actuated by Fluid- Pressure; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This application is a divisionof the application filed by me on December 17, 1904:, Serial No. 237,307.

This invention relates to percussive handtools actuated by fluid-pressure; and it consists principally in a compound-acting hand portable pneumatic hammer Whose piston strikes blows on a separate or removable tool or toolshank fitted in the front end of the cylinder and in which a distributing-valve in the hammer cylinder or casing controls the admission of the motive fluid to the rear end or smaller area (high-pressure head) of the piston and when the forward or effective stroke of the piston is completed acts to cut off the further supply of motive fluid to the rear end of the piston, while at the same time the motive fluid is admitted from the rear end (high-pressure head) of the piston to the front end or larger area (low-pressure head) of the piston, so as to give the rearward or return stroke, and when this return stroke is completed the valve operates to again admit motive fluid from the source of supply to the rear end of the cylinder or small area of the piston, this cycle of operations being continued as long as the throttle-valve controlling the admission of motive fluid to the cylinder is open.

The invention further consists in details and combinations of parts, as hereinafter set forth.

The accompanying drawings illustrate a method of carrying out the invention.

Figure 1 is a longitudinal sectional elevation of a hand portable pneumatic hammer constructed in accordance with this invention. Fig. 2 is a sectional view of the hammer shown in Fig. 1, taken on the line A B, Fig. 6. Fig. 3 is a detail view of the live-air-inlet ports in the throttle-valve, as hereinafter described.

I Figs. at, 5. and 6 are transverse sections of the The same numbers indicate the same parts in the several figures of the drawings.

The hammer cylinder or casing consists of the parts 1 and 2, the part 2 being screwed into the enlarged bore at the rear end of part 1, as shown, or the part 2 may be otherwise conveniently attached to the part 1.

3 is the cylind rical part or handle-base, which is also the throttle-valve, hereinafter more fully described, and 4 is the grasping-handle, which in the construction shown is formed integral with the part 3.

5 is the compressed-air-inlet passage formed in the handle 4 and to which the supply-pipe is connected in the known manner.

6 is an annular recess provided in the cylindrical part 3, said recess being in constant communication with the inlet-passage 5, thus forming a live-air chamber.

7 is a bush or sleeve, of gun-metal or other suitable material, which is pressed into or otherwise securely fixed in the cylindrical part 3. The flange 7 at the forward or lefthand end of bush 7 bears on a series of balls 8, provided in pockets or in a ball-race formed in an annular projection or ring 9, provided on the part 2 of the hammer-cylinder. It is not essential that the flange 7 be provided. Preferably at least two springcontrolled catches or pawls 10 (see Fig. 2) are provided in recesses at opposite positions in the ring 9 as a means of checking or controlling the rotation of the parts 3 and 7 (throttlegalve) on the rear end or part 2 of the cylin- 11 is a lock-nut on the rear end of the cylinder for retaining the handle 4: and its connected parts 3 and 7 on the cylinder.

12 is the small area or high-pressure head of the piston-hammer, 13 the larger area or low-pressure head, and 14 a necking or reduced part of the piston connecting the heads 12 and 13.

In the construction shown the automatic distributing-valve consists of a sleeve or cylinder let, provided with radial wings or blades 15 and 16, (see Figs. 2 and 5,) the blade 16 being'of larger area than the blade 15. The

blades 15 and 16 work in chambers or re-. cesses, respectively, 17 and 18, formed in a bushing 19, fitted in the enlarged bore at the rear end of part 1 of the hammer-cylinder. The bush 19 is provided with end rings or walls 20 and 21, which are screwed into or otherwise attached to said bush.

22 22 (see Figs. 2 and 6) are live-air-inlet ports in the throttle-valve bush 7, which ports are in constant communication with the liveair chamber 6. These ports are preferably approximately triangular in shape, as shown in Fig. 3, so that when the throttle-valve is turned to-admit compressed air from the supply-passage 5 and chamber 6 to the live-air ports and passages of the hammer-cylinder, hereinafter referred to, the lowermost parts of the ports 22 (marked 22 in Fig. 3) will be first caused to register with the live-air-inlet ports 23 23, formed in the rear end or part 2 of the hammer-cylinder, so that as the throttle-valve (cylindrical part 3 and bush 7) is further turned the opening of ports 22 into ports 23 will be gradually increased, whereby theadmission of compressed air to the hammer-cylinder is also effected in a graduallyincreasing manner until the full port-opening is obtained. The inlet-ports 23 23 lead into live-air passages or chambers 24 24, formed in the cylinder-wall or part 2 of the casing.

25 25 are longitudinal slots forming long inlet-ports in the cylindrical valve 14, said ports being preferably tapered or reduced in size at the rear end, as shown in Fig. 1.

26 26 are longitudinal slots or ports leading from the live-air passage 24 to the exterior of the cylindrical valve 14 (or highpressure-piston chamber) when the valve is in the position shown, with its ports 25 registering with the ports 26.

27 27 are longitudinal slots or ports leading from the interior of the part 2 of the cylinder or easing into passages 28 28, leading to the larger area or low-pressure head 13 of the piston, said passages being formed in the wall of the cylinder or casing, with a connecting passage or passages through the bush 19.

29 29 are exhaust ports or passages formed in the wall of the rear end or part2 of the hammer cylinder or casing and opening into the atmosphere at the rear.

30 30 are longitudinal slots or ports leading from the passages 29 inward through the wall of the cylinder or part 2, as shown.

31 31 (see Fig. 6) are exhaust grooves or channels formed in the exterior of the cylindrical valve 14, whereby the compressed air is exhausted from the front end of the cylinder or larger (low) pressure-head 13 of the piston, as hereinafter described.

32 (see Fig. 1) is a segmental slot forming a transverse port in the throttle-valve bush 7, which port is in constant communication with the live-air chamber 6 and with a small passage 33, leading into the chamber 17 in bush 19, for the purpose of operating the valve to one of its positions, as hereinafter explained.

34 is a small port provided in the cylindrical valve 14 and leading into the chamber 18 of bush 19 for the purpose of operating the valve 14 to its other position, as hereinafter described. 35 is another small port inthe distributing-valve 14, said port also communicating with chamber 18 for the purpose of exhausting compressed air from said chamher, as hereinafter described.

The space 36 in the hammer cylinder or casing is always open to exhaust to the atmosphere through ports 37 37.

38 38 and 38 38* are exhaust-ports leading from the space 36 in the cylinder into exhaust-passages 39 39, leading to the atmosphere, as shown.

40 is a riveting-tool carried in a recess in the front end of the hammer-cylinder, said tool being provided with a comparatively small shank 41, adapted to be struck by the piston-hammer on its forward stroke. A toolshank of the smallest practicable cross-section provides a minimum area for the motive fluid in the front end of the cylinder to react on, and consequently tends to lessen the jar or shock on the hand of the operator. Although a riveting-tool is shown, it is obvious that other tools may be substituted therefor.

42, Fig. 5, is a small exhaust-port connecting one end or side of chamber 17, and consequently one side of the valve-wing 15, to the atmosphere, and 43 is a similar exhaustport connecting one end or side of chamber 18, and consequently one side of valve-wing 16, with the atmosphere.

44 is an annular or curved groove or recess in the end wing 21 of the bushing 19, (or it might be in the bushing itself,) the passages 28, passing through the bushing 19, opening or leading into said groove, whereby if in assem bling the parts of the hammer the portions of the passages 28 in the cylinder-wall do not register properly with the corresponding parts of the said passages 28 in bushing 19 the necessary communication between the high and low pressure piston-chambers for conveying the motive fluid to the low-pressure-piston head is maintained by means of the groove 44.

45 is a small leak-port in the ring or end 21 of the bushing 19, connecting the groove 44 with the chamber 18, whereby a further supply of motive fluid is admitted to the largerarea wing 16 of the valve 14 to insure that the valve remains in the proper position during the rearward or return stroke of the piston.

parts 3 and 7that is, the throttle-valve-to have been turned to the position shown, with ports 22 in bush 7 registering with the ports 23 in the wall of the cylinder or casing, compressed air will be admitted from the annular live-air chamber 6 through the ports 22 and -23 and into the live-air chambers or passages 24, and with the distributing-valve 14 in the position shown the compressed air will pass from chambers 24, through the longitudinal ports 26 in the cylinder-wall and 25 in the Valve 14, into the rear end of the cylinder or The working is as follows: Assuming the i high-pressure-piston chamber and drive the piston forward to strike the tool-shank 11, the low-pressure head or larger area 13 of the piston being at the same time open to exhaust through the passages 28 in the cylinder-wall and through the ports 27 leading therefrom, and thence by the exterior grooves 31 in the valve 14 through the ports 30 into the exhaustpassages 29 and thence to the atmosphere. hen the rear end or high-pressure head 12 of the piston-hammer has reached the position shown, the small port 3 1 is uncovered thereby and compressed air is admitted through said port from the interior of the valve 14: (high-pressure-piston chamber) into the chamber 18 in bush 19 and there acting on the larger-area wing 16 of the valve 14 overcomes the constant live-air pressure in the chamber 17 (which pressure in chamber 17 was acting on the smaller-area wing 15, so as to hold the valve in the position shown, being admitted to said chamber 17 through the constant live-air port and passage 32 33,) and so partially rotates the valve 14, whereby the ports 25 in said valve are caused to register with the ports 27 and passages 28, leading to the front end of the cylinder or low-pressure head of the piston, while at the same time the admission of compressed air from the live-air chambers 24: to the high-pressure-piston chamber is cut off by the valve 1 1. The compressed air thus admitted through passages 28 to the front end of the cylinder acts on the low-pressure head or larger area of the piston, and so moves it rearward, and during this movement of the piston air in the space 36 in the cylinder exhausts through the ports 38 38 and 38 38 and passages 39 to the atmosphere until the low-pressure head 13 covers the ports 38 38 38 38, after which air in the space 36 will exhaust to the atmosphere through the ports 37. On the completion of the rearward stroke of the piston-hammer or when the rear or right-hand end or shoulder of the necking 1 1 of the piston uncovers the port 35 the compressed air in chamber 18 (admitted thereto through port 34, as previ ously described) will exhaust through the port 35 into the space between the necking 1 1 and the inner wall of the valve 1 1 or highpressure cylinder and thence into the space '36 and through the ports 37 to the atmosphere, whereupon the live air in chamber 17, admitted thereto through port and passage 32 33, as previously described, will reassert itself and by acting on the wing 15 will partially rotate the valve, so as to return it to the position shown, whereupon live air will be again admitted from the annular chamber 6, through the ports 22, 23, 24, 26, and 25, into the high-pressure-piston chamber or rear end of the hammer-cylinder, so' as to again drive I the piston forward to strike the tool-shank 41, and the exhaust from the low-pressurepiston chamber or front end of the pistonhammer will take place through the ports and passages, as hereinbefore described, the reciprocations of the piston continuing in this way so long as the throttle-valve is held in the position to admit compressed air from the source of supply.

This invention provides for the admission of a large volume of motive fluid at a comparatively high rate of speed to both the high and low pressure piston-heads.

The rotatable cylindrical throttle-valve and the ports and passages in connection therewith provide a very direct inlet for the compressed air, and the fullest possible grasping power of the operators hand on the handle 1 is obtainable.

I do not wish to limit myself entirely to the use of the distributing-valve 14 as described and shown, as its construction and method of operation might be varied without altering the functions of the valve. Neither do I limit myself to the employment of the rotatable throttle-valve, as described and shown, with a compound-acting engine or hammer, as substantially the same throttle-valve can be employed in other types of pneumatic hammers.

Further, variations may be made in the details of construction as described and shown without departing from the main features of the invention.

What 1 claim is 1. In an impact-tool, the combination, with two cylinders of different area, of a piston provided with two heads slidable in the two said cylinders, a slidable tool arranged in the path of the said piston, and a cylindrical valve journaled in the smaller of the two said cylinders which admits a charge of pressure fluid to the rear end of the said smaller cylinder to propel the piston forward and which subsequently admits the said charge to the front end of the larger cylinder to return the piston, the rear part of the said larger cylinder being provided with an open air-port.

2. In an impact-tool, the combination, with two cylinders of different area, of a piston provided with two heads slidable in the two said cylinders, a slidable tool arranged in the path of the said piston, an oscillatory valve which admits a charge of pressure fluid to the rear end of the smaller cylinder to propel the piston forward and which subsequently admits the said charge to the front end of the larger cylinder, and means for oscillating the said valve automatically, the rear part of the said larger cylinder being provided with an open air-port.

3. In an impact-tool, the combination, with two cylinders of diflerent area, of a piston provided with two heads slidable in the two said cylinders, a slidable tool arranged in the path of the said piston, a cylindrical distributing-valve for pressure fluid journaled on the rear end portion of the larger cylinder, a handle provided with a cylindrical socket which is journaled on the said valve, said cylinders, larger cylinder being also provided with an valve and socket being provided with ports open air-port.

and passages which admit a charge of pres- In testimony WhereofI affix my signature in sure fluid to the rear end of the smaller eylinpresence of two Witnesses. der to propel the piston forward and which HENRY POTTER subsequently admit the said charge to the front end of the larger cylinder to return the Witnesses:

piston, and means for oscillating the said EUSTAOE H. BARKER, valve automatically, the rear part of the said LESLIE G. VVHEELER. 

